2 * Monitoring code for network dropped packet alerts
4 * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
7 #include <linux/netdevice.h>
8 #include <linux/etherdevice.h>
9 #include <linux/string.h>
10 #include <linux/if_arp.h>
11 #include <linux/inetdevice.h>
12 #include <linux/inet.h>
13 #include <linux/interrupt.h>
14 #include <linux/netpoll.h>
15 #include <linux/sched.h>
16 #include <linux/delay.h>
17 #include <linux/types.h>
18 #include <linux/workqueue.h>
19 #include <linux/netlink.h>
20 #include <linux/net_dropmon.h>
21 #include <linux/percpu.h>
22 #include <linux/timer.h>
23 #include <linux/bitops.h>
24 #include <linux/slab.h>
25 #include <net/genetlink.h>
26 #include <net/netevent.h>
28 #include <trace/events/skb.h>
29 #include <trace/events/napi.h>
31 #include <asm/unaligned.h>
36 static void send_dm_alert(struct work_struct
*unused
);
40 * Globals, our netlink socket pointer
41 * and the work handle that will send up
44 static int trace_state
= TRACE_OFF
;
45 static DEFINE_MUTEX(trace_state_mutex
);
47 struct per_cpu_dm_data
{
48 struct work_struct dm_alert_work
;
49 struct sk_buff __rcu
*skb
;
50 atomic_t dm_hit_count
;
51 struct timer_list send_timer
;
54 struct dm_hw_stat_delta
{
55 struct net_device
*dev
;
56 unsigned long last_rx
;
57 struct list_head list
;
59 unsigned long last_drop_val
;
62 static struct genl_family net_drop_monitor_family
= {
63 .id
= GENL_ID_GENERATE
,
67 .maxattr
= NET_DM_CMD_MAX
,
70 static DEFINE_PER_CPU(struct per_cpu_dm_data
, dm_cpu_data
);
72 static int dm_hit_limit
= 64;
73 static int dm_delay
= 1;
74 static unsigned long dm_hw_check_delta
= 2*HZ
;
75 static LIST_HEAD(hw_stats_list
);
76 static int initialized
= 0;
78 static void reset_per_cpu_data(struct per_cpu_dm_data
*data
)
81 struct net_dm_alert_msg
*msg
;
84 struct sk_buff
*oskb
= rcu_dereference_protected(data
->skb
, 1);
86 al
= sizeof(struct net_dm_alert_msg
);
87 al
+= dm_hit_limit
* sizeof(struct net_dm_drop_point
);
88 al
+= sizeof(struct nlattr
);
90 skb
= genlmsg_new(al
, GFP_KERNEL
);
93 genlmsg_put(skb
, 0, 0, &net_drop_monitor_family
,
95 nla
= nla_reserve(skb
, NLA_UNSPEC
,
96 sizeof(struct net_dm_alert_msg
));
99 } else if (initialized
)
100 schedule_work_on(smp_processor_id(), &data
->dm_alert_work
);
103 * Don't need to lock this, since we are guaranteed to only
104 * run this on a single cpu at a time.
105 * Note also that we only update data->skb if the old and new skb
106 * pointers don't match. This ensures that we don't continually call
107 * synchornize_rcu if we repeatedly fail to alloc a new netlink message.
110 rcu_assign_pointer(data
->skb
, skb
);
114 atomic_set(&data
->dm_hit_count
, dm_hit_limit
);
119 static void send_dm_alert(struct work_struct
*unused
)
122 struct per_cpu_dm_data
*data
= &get_cpu_var(dm_cpu_data
);
125 * Grab the skb we're about to send
127 skb
= rcu_dereference_protected(data
->skb
, 1);
130 * Replace it with a new one
132 reset_per_cpu_data(data
);
138 genlmsg_multicast(skb
, 0, NET_DM_GRP_ALERT
, GFP_KERNEL
);
140 put_cpu_var(dm_cpu_data
);
144 * This is the timer function to delay the sending of an alert
145 * in the event that more drops will arrive during the
146 * hysteresis period. Note that it operates under the timer interrupt
147 * so we don't need to disable preemption here
149 static void sched_send_work(unsigned long unused
)
151 struct per_cpu_dm_data
*data
= &get_cpu_var(dm_cpu_data
);
153 schedule_work_on(smp_processor_id(), &data
->dm_alert_work
);
155 put_cpu_var(dm_cpu_data
);
158 static void trace_drop_common(struct sk_buff
*skb
, void *location
)
160 struct net_dm_alert_msg
*msg
;
161 struct nlmsghdr
*nlh
;
164 struct sk_buff
*dskb
;
165 struct per_cpu_dm_data
*data
= &get_cpu_var(dm_cpu_data
);
169 dskb
= rcu_dereference(data
->skb
);
174 if (!atomic_add_unless(&data
->dm_hit_count
, -1, 0)) {
176 * we're already at zero, discard this hit
181 nlh
= (struct nlmsghdr
*)dskb
->data
;
182 nla
= genlmsg_data(nlmsg_data(nlh
));
184 for (i
= 0; i
< msg
->entries
; i
++) {
185 if (!memcmp(&location
, msg
->points
[i
].pc
, sizeof(void *))) {
186 msg
->points
[i
].count
++;
187 atomic_inc(&data
->dm_hit_count
);
193 * We need to create a new entry
195 __nla_reserve_nohdr(dskb
, sizeof(struct net_dm_drop_point
));
196 nla
->nla_len
+= NLA_ALIGN(sizeof(struct net_dm_drop_point
));
197 memcpy(msg
->points
[msg
->entries
].pc
, &location
, sizeof(void *));
198 msg
->points
[msg
->entries
].count
= 1;
201 if (!timer_pending(&data
->send_timer
)) {
202 data
->send_timer
.expires
= jiffies
+ dm_delay
* HZ
;
203 add_timer_on(&data
->send_timer
, smp_processor_id());
208 put_cpu_var(dm_cpu_data
);
212 static void trace_kfree_skb_hit(void *ignore
, struct sk_buff
*skb
, void *location
)
214 trace_drop_common(skb
, location
);
217 static void trace_napi_poll_hit(void *ignore
, struct napi_struct
*napi
)
219 struct dm_hw_stat_delta
*new_stat
;
222 * Don't check napi structures with no associated device
228 list_for_each_entry_rcu(new_stat
, &hw_stats_list
, list
) {
230 * only add a note to our monitor buffer if:
231 * 1) this is the dev we received on
232 * 2) its after the last_rx delta
233 * 3) our rx_dropped count has gone up
235 if ((new_stat
->dev
== napi
->dev
) &&
236 (time_after(jiffies
, new_stat
->last_rx
+ dm_hw_check_delta
)) &&
237 (napi
->dev
->stats
.rx_dropped
!= new_stat
->last_drop_val
)) {
238 trace_drop_common(NULL
, NULL
);
239 new_stat
->last_drop_val
= napi
->dev
->stats
.rx_dropped
;
240 new_stat
->last_rx
= jiffies
;
247 static int set_all_monitor_traces(int state
)
250 struct dm_hw_stat_delta
*new_stat
= NULL
;
251 struct dm_hw_stat_delta
*temp
;
253 mutex_lock(&trace_state_mutex
);
255 if (state
== trace_state
) {
262 rc
|= register_trace_kfree_skb(trace_kfree_skb_hit
, NULL
);
263 rc
|= register_trace_napi_poll(trace_napi_poll_hit
, NULL
);
266 rc
|= unregister_trace_kfree_skb(trace_kfree_skb_hit
, NULL
);
267 rc
|= unregister_trace_napi_poll(trace_napi_poll_hit
, NULL
);
269 tracepoint_synchronize_unregister();
272 * Clean the device list
274 list_for_each_entry_safe(new_stat
, temp
, &hw_stats_list
, list
) {
275 if (new_stat
->dev
== NULL
) {
276 list_del_rcu(&new_stat
->list
);
277 kfree_rcu(new_stat
, rcu
);
292 mutex_unlock(&trace_state_mutex
);
298 static int net_dm_cmd_config(struct sk_buff
*skb
,
299 struct genl_info
*info
)
304 static int net_dm_cmd_trace(struct sk_buff
*skb
,
305 struct genl_info
*info
)
307 switch (info
->genlhdr
->cmd
) {
308 case NET_DM_CMD_START
:
309 return set_all_monitor_traces(TRACE_ON
);
311 case NET_DM_CMD_STOP
:
312 return set_all_monitor_traces(TRACE_OFF
);
319 static int dropmon_net_event(struct notifier_block
*ev_block
,
320 unsigned long event
, void *ptr
)
322 struct net_device
*dev
= ptr
;
323 struct dm_hw_stat_delta
*new_stat
= NULL
;
324 struct dm_hw_stat_delta
*tmp
;
327 case NETDEV_REGISTER
:
328 new_stat
= kzalloc(sizeof(struct dm_hw_stat_delta
), GFP_KERNEL
);
334 new_stat
->last_rx
= jiffies
;
335 mutex_lock(&trace_state_mutex
);
336 list_add_rcu(&new_stat
->list
, &hw_stats_list
);
337 mutex_unlock(&trace_state_mutex
);
339 case NETDEV_UNREGISTER
:
340 mutex_lock(&trace_state_mutex
);
341 list_for_each_entry_safe(new_stat
, tmp
, &hw_stats_list
, list
) {
342 if (new_stat
->dev
== dev
) {
343 new_stat
->dev
= NULL
;
344 if (trace_state
== TRACE_OFF
) {
345 list_del_rcu(&new_stat
->list
);
346 kfree_rcu(new_stat
, rcu
);
351 mutex_unlock(&trace_state_mutex
);
358 static struct genl_ops dropmon_ops
[] = {
360 .cmd
= NET_DM_CMD_CONFIG
,
361 .doit
= net_dm_cmd_config
,
364 .cmd
= NET_DM_CMD_START
,
365 .doit
= net_dm_cmd_trace
,
368 .cmd
= NET_DM_CMD_STOP
,
369 .doit
= net_dm_cmd_trace
,
373 static struct notifier_block dropmon_net_notifier
= {
374 .notifier_call
= dropmon_net_event
377 static int __init
init_net_drop_monitor(void)
379 struct per_cpu_dm_data
*data
;
382 printk(KERN_INFO
"Initializing network drop monitor service\n");
384 if (sizeof(void *) > 8) {
385 printk(KERN_ERR
"Unable to store program counters on this arch, Drop monitor failed\n");
389 rc
= genl_register_family_with_ops(&net_drop_monitor_family
,
391 ARRAY_SIZE(dropmon_ops
));
393 printk(KERN_ERR
"Could not create drop monitor netlink family\n");
397 rc
= register_netdevice_notifier(&dropmon_net_notifier
);
399 printk(KERN_CRIT
"Failed to register netdevice notifier\n");
405 for_each_present_cpu(cpu
) {
406 data
= &per_cpu(dm_cpu_data
, cpu
);
407 reset_per_cpu_data(data
);
408 INIT_WORK(&data
->dm_alert_work
, send_dm_alert
);
409 init_timer(&data
->send_timer
);
410 data
->send_timer
.data
= cpu
;
411 data
->send_timer
.function
= sched_send_work
;
419 genl_unregister_family(&net_drop_monitor_family
);
424 late_initcall(init_net_drop_monitor
);